| submesh | The submesh index. |
uint The offset applied to all vertex indices of this submesh.
Gets the base vertex index of the given submesh.
The base vertex can be used to achieve meshes that are larger than 65535 vertices while using 16 bit index buffers,
as long as each submesh fits within its own 65535 vertex area. Alternatively, 32 bit index buffers can be used
via indexFormat.
另请参阅：SetIndices。